ABSTRACT
In this paper,by means of PCR amplification,site-specific mutagenesis,DNA recombination in vitro and optimization of translation initiation,we constructed a recombinant plasmid pBV-IL-6 that overproduces biologically active human interleukin-6(rhIL-6)in E.coli.The expressed rhIL-6 lacks the first 25 amino acids of mature hIL-6 and accounts for 71% of the total bacteria proteins.The reasons why a deleted rather than mature IL-6 was chosen for expression in E.coli are as follows:1)The specific bio-activities of the deleted hIL-6 are the same as,even more than that of the mature form according to the published data;2)The deleted part of IL-6 coding region is rich in C-G andeasy to form secondary structure in mRNA,which is not good for expression;3)The re-designed region for initiation site of translation encodes a hydrophilic amino-end which favours highly translation initiation and expression of hIL-6 in E.coli.